The Cards came into the contest sporting MLB's best record, and they were taking on the team with the league's worst.
To Fernandez, it was an ideal matchup.
"I was looking forward to this start," the rookie said. "I look forward to every start, but they're a great team. Everybody knows it. They've got great hitters. They've got hitters who can hit it out. They've got guys who are patient. They have guys who will take a 3-2 curveball for a walk. They've got incredible guys, incredible hitters."
Yet, after the two-hour, 48-minute contest concluded with Steve Cishek logging his eighth save, it was the Cardinals singing Fernandez's praises.
"We watched him in the spring and knew that he was going to be a handful today," Cards manager Mike Matheny said. "He threw the ball well. He had a big hit, too, that ended up hurting. He did a lot of things right."
Along with throwing a career-most 107 pitches and reaching double-digit strikeouts in his 13th big league start, Fernandez added a critical two-out RBI single that tied the game at 2 in the second inning.
But it was his dominating stuff that improved his record to 4-3 while enabling the Marlins to improve to 20-46, while the Cardinals fell to 43-24.
"He did a good job of containing us," St. Louis' Jon Jay said. "We jumped out to a lead early and we had some chances, but he got the best of us tonight."
Fernandez, whose fastball topped out at 98 mph on the night, logged all 10 of his strikeouts on breaking pitches. He had one 10-pitch showdown with Matt Holliday end with the slugger swinging through an offspeed pitch.
The highest compliment Fernandez had on the night was a brief exchange he had when he stepped up to bat in the second inning. Turning to All-Star Yadier Molina, the Marlins' rookie expressed his admiration.
"One of the special moments during the game was the first time I went up to hit," Fernandez said. "Molina was catching. I look up to that guy. When they won the World Series and I saw him catch, I said, 'Man, I wish one day, I could shake his hand.' I was in high school back then.
"I told him, 'Hey, it's a pleasure to be playing against you.' He said, 'No, it's my pleasure.' That was pretty great."
What Fernandez is doing is putting his name among some of the game's best.
According to ESPN Stats and Info, Fernandez is the first pitcher under the age of 21 to strike out as many as 10 since Felix Hernandez in 2007.
"Felix, I mean, there is nothing to say about that," Fernandez said. "Great pitcher. He competes. It's just incredible that I'm able to accomplish that. I'll keep working hard and getting better. That's the plan."
The Marlins were able to manufacture enough offense off Jake Westbrook, who gave up five runs (three earned) in five innings.
Giancarlo Stanton added three hits, including two doubles, and two RBIs.
After falling behind by two runs in the first inning, the Marlins claimed the lead in the fourth inning on Greg Dobbs' RBI double to left. In the fifth, Stanton's two-run double to deep left-center padded the lead to 5-2.
Fernandez got off to a shaky start, giving up two runs on three hits in the first inning. One of the runs was unearned due to an error charged to third baseman Ed Lucas.
Matt Carpenter singled to open the game, and with one out, Holliday reached on Lucas' error. Allen Craig lined an RBI single to right, and Molina's single to right produced the second run.
The Marlins tied it at 2 in the second inning, with both runs unearned. Derek Dietrich reached on Carpenter's error to open the inning, and Adeiny Hechavarria singled to center. Jeff Mathis' groundout to second brought in Miami's first run, and Fernandez helped his cause with a two-out run-scoring single.
Fernandez got stronger as the game progressed, striking out the side in order in the third inning.
"I think his competitiveness comes out," Marlins manager Mike Redmond said. "I think he, in his mind, goes, 'Man, that's it. They're not getting any more runs.' He has the ability to make and execute pitches like only a handful of guys I think I've ever seen.
"He gives up a few hits, and then he goes, 'That's it. I'm done giving up hits, and you guys are really going to have to earn the rest of them.' And that's what he did tonight. He settled in after giving up those two runs. They had a few guys that battled him, had some good at-bats, but he was able to finish them and really was in complete control of that game after the first inning."
In the eighth inning, the Cardinals chipped back to 5-4 with a run off Chad Qualls, who hadn't given up a run since May 10 -- a span of 10 1/3 scoreless innings.
David Freese laced a two-out, opposite-field double to trim Miami's lead to one run. Mike Dunn relieved Qualls and doused the threat by striking out Jay, keeping Fernandez in line for the win.
The growing success Fernandez has had in the big leagues, the right-hander maintains, will not go to his head. He points out that he defected from Cuba at age 15, which keeps him humble.
"It was pretty hard for me to get here," Fernandez said. "Not to the big leagues, but to get to the United States first. That's why I am the way I am. I grew up with nothing. I like to help people. I don't think I'm better than anybody.
"To be humble, people will love you more in the long run. That's how I want it to be. I don't want to be a good pitcher. I want to be a great example on the field."